Crystals of a vitamin D derivative and a method for the preparation thereof

ABSTRACT

The present invention provides crystals of the compound represented by formula (I):  
                 
crystals of a vitamin D derivative which are obtained by purifying a crude or preliminarily purified product of the vitamin D derivative through a reverse phase chromatography and then crystallizing the purified derivative from an organic solvent; novel compounds which are formed during the synthesis of a vitamin D derivative as by-product; and a method for purifying a vitamin D derivative or the precursor thereof. The method of the present invention makes it possible to supply a highly purified vitamin D derivative, especially ED-71, in bulk and steadily.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a division of co-pending parent application Ser. No. 10/193,247,filed Jul. 12, 2002, which is a division of Ser. No. 09/202,144, filedDec. 9, 1998, which is the national stage under 35 U.S.C. Section 371 ofInternational Application PCT/JP97/02060 filed Jun. 16, 1977, whichdesignated the United States.

TECHNICAL FIELD

The present invention relates to novel crystals of a vitamin Dderivative and, more specifically, to novel crystals of a vitamin Dderivative which are obtained by purifying the vitamin D derivativethrough a reverse phase chromatography and then crystallizing thepurified derivative from an organic solvent. The present invention alsorelates to a method for purifying a vitamin D derivative which comprisesa crystallization step.

BACKGROUND ART

A variety of vitamin D derivatives are known to have usefulphysiological activities. For example, JP 6-23185 B/1994 discloses thata 1α-hydroxyvitamin D₃ derivative represented by the following generalformula:

wherein R₁ denotes an amino group or the formula OR′ where R′ denotes alower alkyl group having 1 to 7 carbon atoms which is unsubstituted orsubstituted by a hydroxyl group, a halogen atom, a cyano group or anacylamino group, and R₂ denotes a hydrogen atom or a hydroxyl group, isuseful as a therapeutic agent for diseases caused by calcium dysbolismor as an anti-tumor agent.

1α,25-dihydroxy-2β-(3-hydroxypropoxy) vitamin D₃ (also called as ED-71)which is one of the compounds covered by the above general formula is anactive form of a vitamin D derivative having a bone forming action andthus is in a way to be developed as a therapeutic agent forosteoporosis.

Once such a vitamin D derivative is established as a therapeutic agent,it should be highly purified and be supplied in bulk and steadily.Therefore, it is desired to establish a method for manufacturing avitamin D derivative as soon as possible.

In particular, ED-71 has been obtained only in an amorphous form andthere is no reported isolation of ED-71 in a crystalline form.

DISCLOSURE OF THE INVENTION

An object of the present invention is to establish a method forpreparing a highly purified vitamin D derivative, especially ED-71,which makes it possible to supply the product in bulk and steadily.

Another object of this invention is to provide crystals of a vitamin Dderivative which may be obtained by purifying a crude or preliminarilypurified product of the vitamin D derivative.

Another object of this invention is to provide a method for purifying avitamin D derivative which comprises a crystallization step.

A further object of this invention is to provide a method for purifyingthe pre form compound of ED-71, which comprises a crystallization step,and to provide a purified pre form compound obtained by the method.

A still further object of this invention is to provide novel compoundswhich are secondarily formed during the synthesis and purification of avitamin D derivative.

We have conducted extensive research on the following points which areissued during the synthesis and purification of ED-71 from itsprovitamin D derivative (pro form): (1) the effect of impurities in thepro form on the HPLC preparative purification of ED-71; (2) thestability of ED-71 and its previtamin D derivative (pre form) to heat,light and oxygen; (3) the handling of ED-71 which exhibits a highphysiological action even in a extremely small dose; and (4) thepossibility of the purification of ED-71 by crystallization. As a resultof the research, we have found that crystals of ED-71 can be obtained ingram order by recrystallizing the pro form from methanol, subjecting therecrystallized pro form to a photo-reaction at a low temperature andthen a thermal isomerization reaction, purifying the isomerized productby a reverse phase HPLC, concentrating the eluate, and thencrystallizing the residue from ethyl acetate, and have completed thepresent invention. Further, we have determined the structure ofby-products which are originally contained in the pro form or formedduring the photo-reaction and found that some compounds of them arenovel.

According to one aspect of the present invention, crystals of thecompound represented by formula (I):

are provided.

According to another aspect of the present invention, crystals of avitamin D derivative which are obtained by purifying a crude orpreliminarily purified product of the vitamin D derivative through areverse phase chromatography and then crystallizing the purifiedderivative from an organic solvent, are provided.

According to a further aspect of the present invention, a method forpurifying a vitamin D derivative which comprises subjecting the vitaminD derivative to a reverse phase chromatography is provided.

According to a further aspect of the present invention, a method forpurifying a vitamin D derivative which comprises crystallizing thevitamin D derivative from an organic solvent is provided.

According to a further aspect of the present invention, a method forpurifying a vitamin D derivative which comprises purifying a crude orpreliminarily purified product of the vitamin D derivative through areverse phase chromatography and then crystallizing the purifiedderivative from an organic solvent is provided.

According to a further aspect of the present invention, a method forpurifying the compound represented by formula (II):

which comprises recrystallizing a crude or preliminarily purifiedproduct of the compound represented by formula (II) from an alcohol isprovided.

According to a further aspect of the present invention, a purifiedproduct of the compound represented by formula (II):

which is obtained by recrystallizing a crude or preliminarily purifiedproduct of the compound represented by formula (II) from an alcohol isprovided.

According to a further aspect of the present invention, a method forpreparing a purified product of the vitamin D derivative represented byformula (I):

which comprises recrystallizing a crude or preliminarily purifiedproduct of the compound represented by formula (II):

from an alcohol, subjecting the recrystallized compound of formula (II)to an ultraviolet light radiation and then a thermal isomerizationreaction to give a vitamin D derivative represented by formula (I),purifying the crude or preliminarily purified vitamin D derivative offormula (I) through a reverse phase chromatography, and crystallizingthe vitamin D derivative of formula (I) from an organic solvent, isprovided.

According to a still further aspect of the present invention, thecompound represented by formula (III):

and the compound represented by formula (IV):

are provided. These compounds are contained in the reaction mixtureobtained by the ultraviolet light radiation and the subsequent thermalisomerization reaction of the pro form of ED-71.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a molecular structure projective view showing the structure ofED-71 crystal.

FIG. 2 is a molecular structure stereographic projective view showingthe structure of ED-71 crystal.

FIG. 3 is a molecular structure projective view showing the structure ofED-71 crystal where hydrogen bonds are focused.

FIG. 4 is a molecular structure projective view showing the structure ofED-71 crystal where hydrogen bonds are focused.

PREFERRED EMBODIMENTS OF THE INVENTION

As used herein, the term “vitamin D derivative” means a compound havingthe partial structure of formula (V):

The vitamin D derivative is preferably the compound represented byformula (VIA), (VIB) or (VIC):

wherein R₁ denotes (1) an amino group; (2) —OR₅ where R₅ is a loweralkyl, a lower alkenyl or a lower alkynyl group, each of which may besubstituted by a hydroxyl group, a halogen atom, a cyano group, an aminogroup, an acylamino group or a lower alkoxy group; or (3) a lower alkylgroup, a lower alkenyl group or a lower alkynyl group, each of which maybe substituted by a hydroxyl group, a halogen atom, a cyano group, anamino group, an acylamino group or a lower alkoxy group; R₂, R₃ and R₄each denotes an alkyl group having 1 to 10 carbon atoms, an alkenylgroup having 2 to 10 carbon atoms, or an alkynyl group having 2 to 10carbon atoms, each of which may be substituted by one or more hydroxylgroups; and A denotes a sulfur or oxygen atom.

In the above definition of substituents, the term “lower” means thenumber of carbon atoms contained in the group qualified by the term, forexample, 1 to 7 for alkyl group, 2 to 7 for each of alkenyl and alkynylgroups, and 1 to 7 for alkoxy group.

The vitamin D derivative is more preferably 1α-hydroxyvitamin D₃,1α,25-dihydroxyvitamin D₃, 24,25-dihydroxyvitamin D₃, or the compoundrepresented by formula (VIIA) or (VIIB):

wherein n denotes an integer of 1 to 7, or the compound represented byformula (VIIIA) or (VIIIB):

wherein A denotes a sulfur or oxygen atom.

Especially preferred vitamin D derivative is the compound represented byformula (VIIA):

wherein n denotes an integer of 1 to 7.

The most preferred vitamin D derivative is the compound represented byformula (IX):

which is also called as ED-71.

As used herein, the term “crystal” is used in its broadest meanings andthus is not limited by the crystal form, the crystal system or the like.

Crystals of ED-71 which is the most preferred vitamin D derivative ofthe present invention is not limited by any physical property, as statedpreviously. However, they are particularly preferred to have thefollowing properties: (1) Appearance: white crystalline powder on avisual or fluorescent-microscopic inspection; (2) Solubility: completelysoluble at a concentration of 1 mg/mL in ethanol; (3) Identificationmeans: IR or NMR method; (4) Melting point: 130□ or higher as measuredby DSC; (5) Absorbance index: ∈=16000 or higher as measured at aconcentration of 40 μg/mL in ethanol at 265 nm; and (6) HPLC purity: 97%or higher on the basis of the area under the peak of ED-71 relative tothat under the total peaks recorded in HPLC under the followingconditions; DIACHROMA ODS N-20 5 μm 4.6×250 mm, 45% acetonitrile-water,a flow rate of 1 mL/min, 220 nm, 1 mg/mL 10 μL, 4-90 minutes.

According to one aspect of the present invention, crystals of a vitaminD derivative which may be obtained by purifying a crude or preliminarilypurified product of the vitamin D derivative through a reverse phasechromatography and then crystallizing the purified derivative from anorganic solvent, as well as a method for purifying a vitamin Dderivative which comprises subjecting the vitamin D derivative to areverse phase chromatography and/or crystallizing the purified vitamin Dderivative from an organic solvent are provided.

As used herein, the term “crude or preliminarily purified product” meansa vitamin D derivative product which is obtained from the synthesis ofthe vitamin D derivative without or with a conventional purificationimmediately after the synthesis reaction, and it is usually in anamorphous form.

As used herein, the term “reverse phase chromatography” means thechromatography system in which the stationary phase has a polarity lowerthan the mobile phase. A high performance liquid chromatography (HPLC)is preferred as the reverse phase chromatography.

It will be necessary to appropriately choose eluent, column packing andload onto the column in order to effectively separate the substance ofinterest.

Examples of the eluent include, but not limited to, acetonitrile/waterand acetonitrile/methanol/water. The mixing ratio of the solvents usedfor the above mentioned eluents will vary depending upon such factors asthe substance to be purified and column packing to be used and thus anoptimum ratio of the solvents for a specific application may bedetermined by one of ordinary skill in the art. The ratio ofacetonitrile/methanol/water will generally fall within the range of20-60/0-40/0-80 parts by weight.

The column packing may be chosen in respect to its particle diameter andpore size while taking the compatibility of the column packing with thesubstance to be purified and the column to be used into consideration.

The load onto the column will also vary depending on the internaldiameter of the column and the like. However, the load may be, forexample, about 25 μg to 10 g, preferably about 25 μg to 3 g when theinternal diameter is 50 mm.

The fraction obtained by carrying out the chromatography as describedabove should be treated to isolate the solute contained in the fractionprior to crystallization. The procedures for isolation includesevaporation, freeze-drying, extraction and filtration. From theseprocedures for isolation, one can choose one or more procedures suitableto the substance to be purified by considering the properties of thesubstance. For example, an evaporation is operationally advantageous forthe purification of ED-71, since it is reproducible and ED-71 is notdecomposed.

The organic solvent which may be used for the crystallization of thevitamin D derivative is preferably an aprotic organic solvent. Examplesof the aprotic organic solvent include esters such as ethyl acetate,ketones such as acetone, ethers such as diethyl ether and diisopropylether, acetonitrile, and a mixture thereof, preferably ethyl acetate,acetone, acetonitrile, and a mixture thereof.

Crystallization conditions will vary depending on such factors as thesubstance to be purified and the solvent to be used and thus suitableconditions for a specific application may be determined by one ofordinary skill in the art. However, the crystallization will begenerally carried out by using a solvent in an amount 1-100 times andpreferably 5-10 times more than a crude vitamin D derivative at atemperature of not higher than 30° C. and preferably not higher than−10° C.

According to one aspect of the present invention, a method for purifyingthe compound represented by formula (II):

which comprises recrystallizing a crude or preliminarily purifiedproduct of the compound from an alcohol, as well as the compound offormula (II) purified by the method are provided.

The alcohol used for this recrystallization is methanol.

The physical properties of the compound represented by formula (II)which has been purified by the recrystallization from an alcohol asabove is not limited to any values. However, it is particularlypreferred to have the following properties: (1) Appearance: from whiteto yellow crystalline powder on a visual or fluorescent-microscopicinspection; (2) Solubility: completely soluble at a concentration of 2mg/mL in ethanol (the solution may be from water-white to yellow); (3)Identification means: IR and NMR methods; (4) Water content: 3.0% orlower as measured by Karl-Fischer method using 100 mg of sample; (5)Absorbance index: ∈=10000 or higher as measured at a concentration of100 μg/mL in ethanol at 282 nm; (6) HPLC purity: 85% or higher on thebasis of the area under the peak of the compound represented by formula(II) relative to that under the total peaks recorded in HPLC and noobservable peak between the peaks of the pro form and unP₄ in the HPLCunder the following conditions; DIACHROMA ODS N-20 5 μm 4.6×250 mm, 55%acetonitrile-water, a flow rate of 1 mL/min, 220 nm, 1 mg/mL 10 μL, 4-70minutes; and (7) Content: 85% or higher in HPLC carried out using aninternal standard under the following conditions; YMC Pack ODS A-303 5μm 4.6×250 mm, 55% acetonitrile-water, a flow rate of 1 mL/min, 220 nm.

The following examples are provided in order to further illustrate thepresent invention but should not be construed as limiting the scopethereof.

EXAMPLES Example 1 Synthesis and Purification of2α-(3′-hydroxypropoxy)-5,7-cholestadiene-1α,3β-triol (pro form)

A mixture of epoxy compound (1) (1.00 g, 2.41 mmol), potassiumtert-butoxide (0.75 g, 6.68 mmol) and 1,3-propanediol (20 ml) wasstirred at room temperature for 10 minutes. Then, the reaction mixturewas heated to an internal temperature of 95° C. and stirred for 5 hoursat this temperature. The reaction mixture was poured into a saturatedaqueous solution of ammonia (40 ml) with stirring. After stirring atroom temperature (25-35° C.) for 10 minutes, crystals formed werecollected on a filter and washed with distilled water (20 ml) threetimes. The crude crystals containing water (6.3 g) were stirred inacetonitrile (20 ml) at room temperature (27-22° C.) for 1 hour. Thecrystals were collected on a filter and washed with acetonitrile (5 ml)twice and then dried to give the pro form compound (2) (0.96 g, 81%yield).

The pro form compound (2) thus obtained (29.0 g) was heated to dissolvein methanol (290 ml) previously pretreated by passing argon gas and thenthe resulting solution was filtered through a Kiriyama filter paper(No.4) while hot. After cooling to room temperature, a seed was added tothe solution to induce crystallization. After further cooling to below−10° C., crystals thus formed were collected on a filter and washed with29 ml of cold methanol twice. Then, the crystals were dried in vacuo atroom temperature to give 22.9 g of purified pro form (79.1% recovery,92.1% net recovery). The physical data of the purified pro form are asfollows:

NMR (CD₃OD) and IR (KBr): indicated to be the title compound;

TLC (CH₂ Cl₂:EtOH=9:1): only one spot developed (Rf 0.5);

HPLC purity (220 nm): 98.7%;

Content: 97.1% (internal standard method); and

DSC: peak min. 95.6° C. and 163.2° C., peak max. 120.20° C.

Example 2 Synthesis and Purification of(1R,2R)-1,25-dihydroxy-2-(3′-hydroxypropoxy)-cholecalciferol;2β-(3′-hydroxypropoxy)-(1α,3β,5Z,7E)-9,10-secocholesta-5,7,10(19)-triene-1,3,25-triol(ED-71)

The purified pro form (2) obtained in Example 1 (6.02 g) was dissolvedin THF (1L) in a 1 L vessel and the solution was UV light-irradiatedwith 400 W lamp having a high pressure of mercury vapor through a Vycorfilter at a cooled condition (an internal temperature of below −13° C.)for 150 minutes under a stream of argon. After allowing to rise to roomtemperature, the reaction solution was poured from the vessel into a 2 Leggplant type flask while the vessel was washed with fresh THF (100 mL).The combined solution was heated under reflux for 180 minutes. Afterconcentrating the reaction mixture, the resulting residue was dissolvedin methanol (80 mL) to form a separation sample. Using a pump, 20 mL ofthe sample containing 1.5 g of solute as calculated and expressed as thepro form was placed on the preparative chromatography column having ainternal diameter of 50 mm and a length of 300 mm and packed withDIACHROMA ODS N-20 having a particle diameter of 5 μm which iscommercially available from Mitsubishi Kakouki Co.). 45% acetonitrile inwater was passed through the column at a flow rate of 60 ml/min and theeluate was monitored with UV-light at 220 and 305 nm. About 2.4 LED-71-containing fractions were collected for the time period from about130 to 170 minutes after starting the chromatography. This series ofprocedures was repeated a further 3 times, the pooled fractions of ED-71being about 9 L in total. The combined fractions were then concentratedusing 10 L rotary evaporator. The residue was dissolved in ethanol andthe solution was evaporated to dryness again. The resulting residue wasthen taken up with ethyl acetate (20 ml) and the solution was stirred atroom temperature to precipitate crystals. The suspension was furthercooled to below −10° C. and stirred for 15 minutes at this temperature.The crystalline material was filtered off, washed with cooled ethylacetate (6 ml) three times, and dried in vacuo at room temperatureovernight to give ED-71 (2.17 g, 36.1% yield).

HPLC purity: 99.8% (220 nm), 99.9% (265 nm)

UV (EtOH): λ_(max) 265.4 nm (E17100)

DSC: 135.3° C. (peak min), 122 mJ/mg

Residual solvent (GC method): 1.24% (EtOAc), 0.24% (EtOH)

IR (cm⁻¹): 3533, 3417, 3336, 2943, 2918, 2862, 1649, 1470, 1444, 1416,1381, 1377, 1342, 1232, 1113, 1078, 1072, 1045, 999, 974, 957, 955, 924,910, 895, 868, 833, 796, 764, 663, 634, 594, 472

Example 3 Physical Data of Related Compounds

Some analogues which were formed during the photo- and thermalisomerization reactions were isolated and structurally determined andthen characterized. ED-71 and the pro form thereof obtained in Examples1 and 2 were also characterized in detail. Note that the physical datareported below are from samples further purified by recrystallizationand the like of the analogues.

Melting points are not corrected. IR spectra were determined in JEOLJIR-6000 by KBr tablet method. ¹H-NMR and ¹³C-NMR spectra weredetermined through utilization of JEOL JNM-270EX. TMS was used as aninternal standard for ¹H-NMR and a peak of CHCl₃ was used as a standardfor ¹³C-NMR. UV were determined through utilization of HITACHI U-3210 inethanol at room temperature.

Physical data of pro form of ED-71 which was obtained in Example 1:

¹H-NMR (ppm): 0.63(3H,s), 0.96(3H, d, J²⁰⁻²¹=6.3 Hz), 1.07(3H, s), 1.22(6H, s), 3.6-4.0(7H, m), 5.36-5.40(1H, m), 5.70-5.73(1H, m)

¹³C-NMR (ppm): 141.1, 136.6, 120.8, 115.1, 82.2, 71.0, 70.9, 68.3, 66.7,59.8, 55.7, 54.4, 44.1, 42.9, 41.3, 39.0, 38.3, 36.3, 36.0, 34.6, 32.0,28.8, 28.7, 27.9, 22.9, 20.7, 20.5, 18.6, 15.8, 11.7

UV; λ_(max)(∈): 294.2 nm (6550), 282.2 nm (11300), 271.9 nm (10500),204.7 nm (2420)

IR (cm⁻¹): 3385, 2941, 2872, 1471, 1468, 1381, 1379, 1327, 1138, 1082,1080, 1053

Physical data of ED-71:

¹H-NMR (ppm): 6.37(1H, d; 11.4 Hz), 6.05(1H, d; 11.4 Hz), 5.50(1H, t;2.1 Hz), 5.08(1H, t; 2.1 Hz), 4.32(1H, d; 8.9 Hz), 4.26(1H, m),3.88-3.96(1H, m), 3.85(2H, t; 5.7 Hz), 3.69-3.77(1H, m), 3.27(1H, dd;9.0 Hz, 2.8 Hz), 2.78-2.83(1H, m), 2.55(1H, dd; 10.6 Hz, 4.0 Hz),2.42(1H, bd; 13.6 Hz), 1.8-2.1(5H, m), 1.22(6H, s), 1.2-1.7(11H, m),0.94(3H, d; 6.3 Hz), 0.9-1.1(1H, m), 0.55(3H, s)

¹³C-NMR (ppm): 144.2, 143.0, 132.2, 124.9, 117.2, 111.8, 85.4, 71.6,71.1, 68.3, 66.6, 61.1, 56.6, 56.4, 45.9, 44.4, 40.5, 36.4, 36.1, 31.9,29.3, 29.2, 29.1, 27.7, 23.7, 22.4, 20.8, 18.8, 11.9

UV; λ_(max): 265.4 nm (ε7900)

Melting point: 134.8-135.8° C. (1° C./min),

DSC: 137° C. (peak min, 115 mJ/mg),

TG/DTA: 138° C. (peak min, dry weight loss on melting: about 1%, testsample 1.96 mg),

IR (cm⁻1): 3533, 3417, 3336, 2943, 2918, 2862, 1649, 1470, 1444, 1416,1381, 1377, 1342, 1232, 1113, 1078, 1072, 1045, 999, 974, 957, 955, 924,910, 895, 868, 833, 796, 764, 663, 634, 594, 472

Lumi form of ED-71 which is represented by the formula:

HPLC purity: 97.5% (220 nm)

¹H-NMR (ppm): 5.75(1H, d, J=5.3 Hz), 5.42-5.44(1H, m), 4.19(1H, q, J=2.9Hz), 3.8-4.0(4H, m), 3.6-3.7(1H, m), 3.25(1H, dd, J=2.6 Hz, 9.6 Hz),1.21(6H, s), 0.90(3H, d, J=5.6 Hz), 0.82(3H, s), 0.58(3H, s)

¹³C-NMR (ppm): 141.9, 136.2, 123.3, 115.5, 82.8, 77.9, 71.1, 67.4, 64.9,61.1, 57.2, 49.5, 46.7, 44.4, 43.8, 41.4, 37.5, 36.2, 35.9, 32.0, 29.4,29.2, 28.8, 22.6, 21.4, 20.9, 18.5, 18.3, 8.5

UV; λ_(max): 273.5 nm (ε9010)

IR (cm⁻¹): 3437, 3383, 3309, 3041, 2960, 2935, 2872, 2787, 1657, 1641,1470, 1441, 1375, 1257, 1205, 1203, 1167, 1128, 1097, 1074, 1039, 1011,980, 935, 908, 885, 820, 781, 779, 723, 671, 613

Tachy form of ED-71 which is represented by the formula:

HPLC purity: 97.6% (220 nm)

¹H-NMR (ppm): 6.65(1H, d, J=16.1 Hz), 6.10(1H, d, J=16.1 Hz), 5.73(1H,d, J=2.8 Hz), 4.21-4.25(2H, m), 3.70-3.90(4H, m), 3.45(1H, dd, J=2.4 Hz,6.0 Hz), 1.91(3H, s), 1.22(6H, s), 0.98(3H, d, J=6.5 Hz), 0.69(3H, s)

¹³C-NMR (ppm): 138.1, 130.9, 129.5, 127.8, 126.0, 124.5, 83.1, 72.4,71.1, 68.5, 65.3, 61.1, 54.0, 50.0, 44.4, 42.8, 36.4, 36.0, 35.9, 31.9,31.4, 29.4, 29.2, 28.7, 25.1, 24.3, 20.8, 18.7, 15.1, 11.2

UV; λ_(max): 281.4 nm (ε26100)

IR (cm⁻¹): 3375, 2945, 2875, 1664, 1632, 1612, 1468, 1429, 1377, 1215,1157, 1095, 1068, 957, 908, 879, 764, 710, 646

Pre form of ED-71 which is represented by the formula:

HPLC purity: 97.2% (220 nm)

¹H-NMR (ppm): 5.91, 5.78(1H×2, d, J=12 Hz), 5.52(1H, d, J=3.3 Hz),4.0-4.2(2H, m), 3.7-4.0(4H, m), 3.43(1H, dd), 1.76(3H, s), 1.22(6H, s),0.96(3H, d, J=6.6 Hz), 0.70(3H, s)

UV; λ_(max): 206 nm (ε10300)

IR (cm⁻¹): 3377, 2949, 2947, 2872, 1643, 1470, 1435, 1406, 1379, 1377,1263, 1215, 1140, 1119, 1088, 1063, 1047, 1032, 1030, 962, 937, 935,756, 735,

Example 4 X-ray Crystal Structure Analysis of ED-71

X-ray diffraction experiments of ED-71 were conducted using acrystalline powder selected from the sample powders, a part of which wasalso used in Example 3. As a result, the crystal was found to be ofrhombic system and have a space group of P2₁,2₁2₁ and lattice constantsof a=10.352 (2), b=34.058 (2) and c=8.231 (1)Å, and Z=4. From theseexperiments, 2520 reflection data were obtained.

A structure analysis was made as follows. A direct method using SHELXS86was employed in determining phases and then the location of each of thenon-hydrogen atoms was determined by a Fourier mapping. For thecarbon-bonded hydrogen atoms, each location of them was determined by acalculation using the location of the carbon atom. For the oxygen-bondedhydrogen atoms, each location of them was determined by a D mappingafter each location of other atoms was determined.

After improving the preciseness of the locations of the non-hydrogen andoxygen-bonded hydrogen atoms and the temperature factor of anisotropyfor the non-hydrogen atoms by the method of least squares, thereliability factor (R value) of the analysis results converged into3.9%. However, the absolute structure of the crystal was not determinedfrom the results directly but by further calculating the results oncondition that the configuration of positions 13, 14, 17 and 20 of ED-71is the same as the corresponding configuration of cholesterol.

FIGS. 1 to 4 show the structure of ED-71 and the hydrogen bonds therein,respectively, which were determined on the basis of the analysisresults.

Reference Example 1 Stability of ED-71 Crystalline Compound

Amorphous and crystalline ED-71 compounds were tested for stability at10□, 250□ and 40□. To estimate the stability, HPLC quantitative assayand absorbance and purity measurements were utilized. The purity wasexpressed as peak area ratio in percentage in HPLC (% P.A.R.). The testwas carried out by using the following procedures:

(1) Procedures of the Stability Test

About 2 mg portions of each of the amorphous and crystalline samples areprecisely weighed into transparent 10 ml test tubes each having screwcap, individually.

The test tubes are purged with argon using a vacuum desiccator and aglove box. This purging procedure is not applied to the test tubesindicated as “1M (air)” in the tables below.

The test tubes in groups are fixed in thermostatic baths which arerespectively controlled at the above temperatures and allowed to standin the dark. After one (1 W) or two (2 W) weeks or one month (1 M), thetest tubes are removed from the baths and subjected to the followingassay and measurements:

(2) HPLC Quantitative Assay

5 ml of absolute ethanol is precisely added to the test tube to form asample solution. 1 ml of the sample solution and 1 ml of an internalstandard solution are both precisely added to another test tube and theresulting mixture is diluted with methylene chloride to give a wholevolume of 20 ml. This diluted solution is designated solution 1. Theinternal standard solution is formed by dissolving 2-aminopyrimidine inmethanol to a concentration of 0.6 mg/ml.

Next, both of 1 ml of another standard solution for quantitative assaywhich is formed by dissolving crystalline ED-71 in absolute ethanol to aconcentration of 0.4 mg/ml and 1 ml of the internal standard solutionare precisely added to another test tube and the resulting mixture isdiluted with methylene chloride to give a whole volume of 20 ml. Thisdiluted solution is designated solution 2.

HPLC is carried out using 20 μl of each of solutions 1 and 2. For eachsolution, an area ratio of the peak of ED-71 to the peak of the internalstandard substance is determined from the HPLC data. The ED-71 contentin the sample is determined from the ratio of the area ratio forsolution 1 to that for solution 2.

Survivability (%) is determined by dividing the ED-71 content thusobtained by ED-71 content in the same sample but prior to the abovetreatment.

HPLC conditions used:

Column: YMC A-004SIL (4.6×300 mm)

Mobile phase: methylene chloride/methanol mixture (95/5)

Flow rate: 1 ml/min

Detection: at UV 265 nm.

(3) Absorbance Measurement

1 ml of the sample solution as prepared in “HPLC quantitative assay”above is diluted with absolute ethanol to give a whole volume of 10 mland this diluted solution is then measured for the absorbance at 265 nmusing a ultraviolet spectrophotometer. The absorbance is converted intoE 1% value which is derived from Lambert-Beer Law and the conversion ismade according to the following equation:E1%=A/cbwherein A is absorbance, c is concentration in g/100 ml and b is lengthof optical path in cm across the test solution, which is commonly 1.(4) Purity Measurement

(4-1) Normal Phase HPLC

1 ml of the sample solution as prepared in “HPLC quantitative assay”above is dried in vacuo to remove the solvent (absolute ethanol). Theresidue is dissolved in 1 ml of methylene chloride. HPLC assay iscarried out using 25 μl of this solution.

HPLC conditions used:

Column: YMC A-004SIL (4.6×300 mm)

Mobile phase: methylene chloride/methanol mixture (96/4)

Flow rate: 1.8 ml/min

Detection: at UV 265 nm.

(4-2) Reverse Phase HPLC

HPLC is carried out using 25 μl of the sample solution as prepared in“HPLC quantitative assay” above.

HPLC conditions used:

Column: Inertsil ODS-2 (5×250 mm)

Mobile phase: acetonitrile/water mixture (55/45)

Flow rate: 1 ml/min

Detection: at UV 265 and 220 nm.

The values of the HPLC quantitative assay and the purity measurement areaveraged over two runs. The results obtained are shown in Tables 1 to 5below. TABLE 1 Results of HPLC Quantitative Assay (% Survivability) 10°C. 25° C. 40° C. Amor. Crys. Amor. Crys. Amor. Crys. 0 100 100 100 100100 100 1 W 99.5 99.4 99.4 99.5 2 W 98.5 96.8 94.7 98.8 88.8 102.9 1 M94.8 97.0 1 M (air) 97.4 95.0Note:All samples were purged with argon except 1 M (air).

TABLE 2 E 1% 10° C. 25° C. 40° C. Amor. Crys. Amor. Crys. Amor. Crys. 0327.5 359.2 327.5 359.2 327.5 359.2 1 W 323.0 349.5 313.2 349.8 2 W324.9 343.8 316.9 341.6 304.0 348.7 1 M 320.5 342.7 1 M (air) 316.3341.7Note:All samples were purged with argon except 1 M (air).

TABLE 3 Purity Measurement Using Normal Phase HPLC (% P.A.R at 265 nm)10° C. 25° C. 40° C. Amor. Crys. Amor. Crys. Amor. Crys. 0 ED-71 96.0699.15 96.06 99.15 96.06 99.15 Pre Form 1.67 0.21 1.67 0.21 1.67 0.21Other 2.27 0.63 2.27 0.63 2.27 0.63 peaks 1 W ED-71 95.97 99.56 94.4799.55 Pre Form 1.88 0.14 2.53 0.14 Other 2.14 0.30 3.00 0.31 peaks 2 WED-71 95.46 99.06 94.74 98.95 92.12 98.92 Pre Form 2.27 0.66 2.25 0.672.99 0.67 Other 2.28 0.27 3.01 0.38 4.89 0.41 peaks 1 M ED-71 94.5898.91 Pre Form 2.33 0.65 Other 3.09 0.44 peaks 1 M (air) ED-71 95.2698.88 Pre Form 2.31 0.66 Other 2.42 0.46 peaksNote:All samples were purged with argon except 1 M (air).

TABLE 4 Purity Measurement Using Reverse Phase HPLC (% P.A.R at 265 nm)10° C. 25° C. 40° C. Amor. Crys. Amor. Crys. Amor. Crys. 0 ED-71 95.3899.04 95.38 99.04 95.38 99.04 Pre Form 1.16 0.36 1.16 0.36 1.16 0.36Other 3.47 0.60 3.47 0.60 3.47 0.60 peaks 1 W ED-71 94.78 99.35 92.4799.40 Pre Form 1.27 0.28 1.98 0.29 Other 3.95 0.38 5.55 0.31 peaks 2 WED-71 94.48 98.84 94.20 98.78 90.68 98.75 Pre Form 1.75 0.83 1.72 0.852.53 0.85 Other 3.77 0.32 4.08 0.37 6.78 0.40 peaks 1 M ED-71 93.0598.77 Pre Form 1.88 0.86 Other 5.07 0.37 peaks 1 M (air) ED-71 94.1198.72 Pre Form 1.82 0.86 Other 4.07 0.42 peaksNote:All samples were purged with argon except 1 M (air).

TABLE 5 220 nm (%) 10° C. 25° C. 40° C. Amor. Crys. Amor. Crys. Amor.Crys. 0 ED-71 93.95 97.44 93.95 97.44 93.95 97.44 Pre Form 1.37 0.521.37 0.52 1.37 0.52 Other 4.70 2.04 4.70 2.04 4.70 2.04 peaks 1 W ED-7193.37 98.17 90.00 98.18 Pre Form 1.50 0.44 2.29 0.47 Other 5.13 1.407.71 1.35 peaks 2 W ED-71 92.85 97.91 92.39 97.56 87.40 97.65 Pre Form2.02 1.01 1.93 1.01 2.88 1.02 Other 5.13 1.09 5.68 1.43 9.72 1.33 peaks1 M ED-71 92.85 97.44 Pre Form 2.02 1.05 Other 5.13 1.51 peaks 1 M (air)ED-71 92.07 97.09 Pre Form 2.04 1.09 Other 5.88 1.82 peaksNote:All samples were purged with argon except 1 M (air).

As can be seen from the tables, the crystalline form has higherstability than the amorphous from up to 2 weeks at 25° C. and 40° C.

INDUSTRIAL APPLICABILITY

The crystals of a vitamin D derivative of the present invention achievean improved purity and stability and steady quality of the vitamin Dderivative, and thus it is useful for preparing a medicament and thelike containing the vitamin D derivative. Further, the method forpurifying a vitamin D derivative of the present invention makes itpossible to supply a highly pure vitamin D derivative in bulk (in gramorder) and steadily.

Furthermore, the tachy and lumi forms which are analogues of ED-71 andthe pro form of ED-71, respectively, are novel compounds and are usefulfor a test or analysis which may be carried out in the synthesis of avitamin D derivative.

1. A method for purifying the compound represented by formula (II):

comprising recrystallizing a crude or preliminarily purified product ofthe compound represented by formula (II) from an alcohol.
 2. The methodaccording to claim 1 wherein the alcohol is methanol.
 3. A purifiedproduct of the compound represented by formula (II)

which is obtained by recrystallizing a crude or preliminarily purifiedproduct of the compound represented by formula (II) from an alcohol. 4.The method according to claim 3 wherein the alcohol is methanol.
 5. Amethod for preparing a purified product of the vitamin D derivativerepresented by formula (I):

comprising: recrystallizing a crude or preliminarily purified product ofthe compound represented by formula (II)

 from an alcohol; subjecting the recrystallized compound of formula (II)to ultraviolet light radiation and then a thermal isomerization reactionto produce a vitamin D derivative represented by formula (I); purifyingthe crude or preliminarily purified vitamin D derivative of formula (I)using reverse phase chromatography; and crystallizing the vitamin Dderivative of formula (I) from an organic solvent.
 6. The methodaccording to claim 5 wherein the organic solvent is an aprotic organicsolvent.
 7. The method according to claim 6 wherein the aprotic organicsolvent is ethyl acetate, acetone, acetonitrile, or mixtures thereof. 8.The method according to claim 5 wherein the alcohol is methanol.
 9. Themethod according to claim 6 wherein the alcohol is methanol.
 10. Themethod according to claim 7 wherein the alcohol is methanol.
 11. Themethod according to claim 8 wherein the alcohol is methanol.
 12. Acompound represented by formula (III):


13. A compound represented by formula (IV):